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Bhat" Subject: [PATCH v5 22/45] infiniband: ehca: Use get/put_online_cpus_atomic() to prevent CPU offline To: tglx@linutronix.de, peterz@infradead.org, tj@kernel.org, oleg@redhat.com, paulmck@linux.vnet.ibm.com, rusty@rustcorp.com.au, mingo@kernel.org, akpm@linux-foundation.org, namhyung@kernel.org Date: Tue, 22 Jan 2013 13:09:13 +0530 Message-ID: <20130122073909.13822.6220.stgit@srivatsabhat.in.ibm.com> In-Reply-To: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> References: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13012207-8878-0000-0000-0000059D7359 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20130122_024111_724962_57A99DF3 X-CRM114-Status: GOOD ( 12.73 ) X-Spam-Score: -1.9 (-) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-1.9 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at http://www.dnswl.org/, medium trust [122.248.162.7 listed in list.dnswl.org] 3.0 KHOP_BIG_TO_CC Sent to 10+ recipients instaed of Bcc or a list -0.7 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Cc: linux-arch@vger.kernel.org, linux@arm.linux.org.uk, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, fweisbec@gmail.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, rostedt@goodmis.org, xiaoguangrong@linux.vnet.ibm.com, rjw@sisk.pl, sbw@mit.edu, wangyun@linux.vnet.ibm.com, srivatsa.bhat@linux.vnet.ibm.com, netdev@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Once stop_machine() is gone from the CPU offline path, we won't be able to depend on preempt_disable() or local_irq_disable() to prevent CPUs from going offline from under us. Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline, while invoking from atomic context. Cc: Roland Dreier Signed-off-by: Srivatsa S. Bhat --- drivers/infiniband/hw/ehca/ehca_irq.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/infiniband/hw/ehca/ehca_irq.c b/drivers/infiniband/hw/ehca/ehca_irq.c index 8615d7c..d61936c 100644 --- a/drivers/infiniband/hw/ehca/ehca_irq.c +++ b/drivers/infiniband/hw/ehca/ehca_irq.c @@ -43,6 +43,7 @@ #include #include +#include #include "ehca_classes.h" #include "ehca_irq.h" @@ -653,6 +654,9 @@ void ehca_tasklet_eq(unsigned long data) ehca_process_eq((struct ehca_shca*)data, 1); } +/* + * Must be called under get_online_cpus_atomic() and put_online_cpus_atomic(). + */ static int find_next_online_cpu(struct ehca_comp_pool *pool) { int cpu; @@ -703,6 +707,7 @@ static void queue_comp_task(struct ehca_cq *__cq) int cq_jobs; unsigned long flags; + get_online_cpus_atomic(); cpu_id = find_next_online_cpu(pool); BUG_ON(!cpu_online(cpu_id)); @@ -720,6 +725,7 @@ static void queue_comp_task(struct ehca_cq *__cq) BUG_ON(!cct || !thread); } __queue_comp_task(__cq, cct, thread); + put_online_cpus_atomic(); } static void run_comp_task(struct ehca_cpu_comp_task *cct) @@ -759,6 +765,7 @@ static void comp_task_park(unsigned int cpu) list_splice_init(&cct->cq_list, &list); spin_unlock_irq(&cct->task_lock); + get_online_cpus_atomic(); cpu = find_next_online_cpu(pool); target = per_cpu_ptr(pool->cpu_comp_tasks, cpu); thread = *per_cpu_ptr(pool->cpu_comp_threads, cpu); @@ -768,6 +775,7 @@ static void comp_task_park(unsigned int cpu) __queue_comp_task(cq, target, thread); } spin_unlock_irq(&target->task_lock); + put_online_cpus_atomic(); } static void comp_task_stop(unsigned int cpu, bool online)